Currently, the specification says:
"For the purposes of document summaries, outlines, and the like,
header elements are equivalent to the highest ranked h1â€“h6 element
descendant of the header element (the first such element if there are
multiple elements with that rank)."
This should say that this only refers to the textual content (as
otherwise it means <header><h3/></header> should have rank 3 instead
of rank 1, among other things).
Also, it is undefined what happens when there is no hn child.
--
Geoffrey Sneddon
<http://gsnedders.com/>